Behaviour of Mandibular Fractures under Earth and Microgravity conditions: A Finite Element Analysis

Behaviour of Mandibular Fractures under Earth and Microgravity conditions: A Finite Element Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Behaviour of Mandibular Fractures under Earth and Microgravity conditions: A Finite Element Analysis Sidharth Manoj, Manoj Kumar K P, Vipin Das A P This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7531616/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 02 Mar, 2026 Read the published version in npj Microgravity → Version 1 posted 9 You are reading this latest preprint version Abstract Maxillofacial fractures especially that of the mandible pose a significant risk under microgravity environments because astronauts experience progressive bone loss during long duration flights because of skeletal unloading. In this study we explore the biomechanical response of mandibular angle under high impact trauma under Earth’s gravity and microgravity. A human mandibular model was subjected to a force of 2000N force at angle of 45° which was directed posterosuperiorly at the right angle region with simulations comparing healthy and osteoporotic bone (bone loses its density in long flights due to skeletal unloading). The results revealed that although stresses remained the same across all conditions microgravity caused nearly double the strain and deformation indicating high risk of fracture. These findings emphasise the need for biomechanical evaluation and protective strategies in space medicine. Health sciences/Diseases Health sciences/Health care Health sciences/Medical research Biological sciences/Physiology Mandible Angle fracture Finite element analysis Microgravity Osteoporosis Spaceflight medicine Maxillofacial trauma Gravity Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Introduction The maxillofacial region being one of the most exposed parts of the body is highly susceptible to trauma. Common causes of maxillofacial trauma include fall, traffic accidents, interpersonal violence and sports injuries [ 1 ] . Of all maxillofacial trauma 42% attribute to mandibular fractures which includes angle fractures (30%), parasymphysis fractures (27%), condylar fractures (27%), body fractures (9%), symphyseal fractures (4%), ramus fractures (3%) and then the coronoid (≤ 1%) [ 2 ] . Biomechanical integrity of the mandible is a necessity for proper speech, mastication and protection of the lower airway and a fracture disrupts this integrity making them clinically significant [ 3 , 4 ] . In the context of long duration spaceflights, the fracture biomechanics is more complex. Long exposures to zero gravity/ microgravity causes marked decrease in bone mineral density and disruption of its trabecular pattern due to a condition called as spaceflight osteopenia [ 5 , 6 ] . Studies shows that astronauts loose about 1-1.5% of their bone mass every month under microgravity because of the absence of mechanical loading which normally induces bone remodelling [ 7 , 8 ] . Maxillofacial region though not studied extensively are not exempted from these degenerative changes [ 9 , 10 , 11 ] . Adding to this is the risk of traumatic injuries in space including unintentional collision with spacecraft equipment, free floating impact or emergency events. Even minor trauma could have more severe repercussions in space where bone weakness is increased and healing is not properly understood [ 12 , 13 ] . As many space missions extend beyond low earth orbit it is necessary to understand the biomechanics of maxillofacial trauma in microgravity. As technology advances newer methods have risen to better understand biomechanics of orthopaedic and maxillofacial bones, one of them being the Finite Element Analysis (FEA) which is being widely used as a predictive tool to evaluate stress-strain response of bones under various loading conditions [ 14 , 15 , 16 ] . FEA of the mandible has been used to understand fracture risk; fracture fixation stability and study how occlusal loads are transferred [ 15 , 16 , 17 ] . FEA studies though highly versatile and efficient no studies have emphasized the biomechanical behaviour of mandible under altered gravitational environments. To address this gap this study focuses on the use of FEA to compare mandible specifically the angle subjected to trauma under Earth’s gravity and microgravity. Also, two different bone qualities of mandible are used in the study that is healthy mandible and an osteoporotic mandible. The aim of this study is to evaluate the biomechanical behaviour of mandibular angle under a moderate to high impact trauma under gravity and microgravity. From the simulation of trauma to osteoporotic and normal bone we aim to quantify the effects of gravitational unloading on fracture risk and deformation patterns. Materials and Methods A CT scan of a human mandible was obtained as a DICOM file which was imported to a CAD software called Fusion 360 (Autodesk, USA). The 3D volume was converted to a surface mesh so that the entire mandible would be recognized as a solid by the FEA software (Ansys) which was then exported as a STEP file. The STEP file was imported into Ansys Workbench 2025 R1 (Ansys Inc., USA) using SpaceClaim (a CAD tool integrated within Ansys) where some geometric refinements and mesh optimizations were performed (Fig. 1 ). For the model meshing was done using a tetrahedral patch independent mesh with an elemental size of 0.3mm to ensure adequate resolution at structurally significant areas like the angle and condyles. Within the engineering data module of Ansys two custom material profiles were created to represent healthy and osteoporotic bones. They were given the following properties [ 18 , 19 , 20 , 21 ] Table 1 Properties of healthy and osteoporotic bones. Bone type Density Youngs modulus Poisson’s Ratio Healthy bone 1900 Kg/ m³ 14 GPa 0.3 Osteoporotic bone 1500 Kg/ m³ 7 GPa 0.3 The prepared model was then imported to static structural environment within Ansys and four of the following simulations were tested Healthy bone under Earth gravity (1g) Osteoporotic bone under Earth gravity Healthy bone under microgravity (0g) Osteoporotic bone under microgravity In all cases fixed supports were applied at the condyles (Fig. 2 ) to simulate the temporomandibular joint. For models involving gravity, the standard earth gravity (9.81m/s²) setting was applied which resulted in a gravitational force in the negative Z direction (Fig. 3 ). To simulate trauma a force of 2000N at angle of 45° posterosuperiorly was given at the right mandibular angle, corresponding to the vector of a moderate to a high impact blow that may occur during interpersonal violence or accidental impact [ 22 , 23 ] . After the boundary conditions were set the models were solved under linear elastic assumptions and outcomes of each simulation were described in terms of Equivalent (von Mises) stress Elastic strain Total deformation These results were compared to understand the role of bone quality and gravitational forces on mandibular biomechanics under trauma Results FEA was performed on the mandibular models under four distinct conditions. Healthy and Osteoporotic bones were tested under Earth’s gravity and microgravity. The results were expressed as equivalent (von Mises) stress, elastic strain, and total deformation. The summarized results are presented in Table 2 . Table 2 Summary of results obtained under different bone types and gravity. Condition Equivalent stress Elastic strain Total deformation Healthy bone under gravity 1.1021e9 0.098353 0.00127 Osteoporotic bone under gravity 1.1017e9 0.098317 0.0012683 Healthy bone under micro gravity 1.1021e9 0.19669 0.0025393 Osteoporotic bone under micro gravity 1.017e9 0.19663 0.0025365 Under Earth gravity, both normal and osteoporotic bone possessed nearly similar stress values (~ 1.1 GPa) with less than 1% difference in deformation and strain. Under microgravity, both conditions elastic strain and overall deformation nearly doubled as compared to their Earth counterparts. Despite the increased deformation and strain, stress values were nearly the same, suggesting that gravity played no role in the internal force distribution but in displacement and material extension. Curiously, the osteoporotic bone in microgravity was under lower stress (1.017 × 10⁹ Pa) than healthy bone but with practically the same strain and deformation. This could be indicative of an impaired load-carrying capability due to impaired stiffness and density, demonstrating the vulnerability of impaired bone tissue in low-gravity conditions. Below are the results of the FEA: Healthy bone under gravity Osteoporotic bone under gravity Healthy bone under micro gravity Osteoporotic bone under micro gravity Discussion This finite element analysis demonstrated that microgravity significantly alters mandibular biomechanical response to trauma and that the effect is enhanced in osteoporotic bone. We present our findings below in the context of the literature. Experimental data from postmortem human mandibles indicate that fracture thresholds at the condyle and mandibular angle are approximately 2,800 N in the condition of restrained impact loading [ 24 , 25 ] . Finite element and experimental studies with controlled direction and magnitude of loading always apply forces of approximately 2,000 N at 45° angulation and induce clinically relevant fracture patterns at the mandible angle [ 22 , 23 ] . These findings justify our choosing a 2,000 N, posterosuperiorly directed, 45° trauma vector to model moderate-to-severe impacts. Our finding that elastic strain and deformation nearly doubled under microgravity is consistent with known alterations in bone response in space. While long bones are well described for microgravity-induced bone loss, craniofacial bones like the mandible are not immune to loss. Simulated microgravity models have shown substantial reductions in mandibular and alveolar bone density and increased resorption markers in males and females [ 11 ] . Similarly, micro-CT analysis in rodents has described substantial mandibular microstructure alterations under spaceflight conditions [ 10 ] . In gravity osteoporotic bone shows only a minimal increase in deformation compared to healthy bone, because the fixed condyle boundary condition dominates structural response, the same reason implies to normal and osteoporotic bone in microgravity as they do not allow any kind of movements. Also, evidence shows osteoporosis lowers bone stiffness and density, which renders it more susceptible to deformation during loading. Experimental testing reveals cortical bone densities in osteoporotic human mandibles to be much lower than that of control healthy subjects, corresponding to reduced elastic modulus (< 10 GPa) and bone mineral density. These results favour both the modulus and density differences used by our model [ 26 , 27 , 28 ] . Biomechanical implications of gravity removal Most FEA trauma analysis ignore gravity on the grounds that high-magnitude forces dominate gravity's effects in brief simulations. However, comparison suggests exclusion of preload under gravity causes greater displacement and strain under identical external loads. Facial bones do not support weight in the conventional sense, so facial structures react differently when gravity is ignored: the mandible is more freely mobile, with no counterforce to dissipate impact energy — this removes baseline tissue resistance and allows more deformation. Clinical and spaceflight relevance The microgravity-induced doubling of strain and deformation poses important concerns over fracture tolerance thresholds in astronauts, particularly those with osteopenia due to spaceflight. Even small impact events such as equipment strikes, floating strikes, or inadvertent drops could be beyond the tolerance of weakened craniofacial bones. This is compelling evidence supporting protective craniofacial equipment, trauma prevention protocols, and pre-launch screening for astronaut applicants for bone mineral density. Limitation and future directions Bone heterogeneity: Mandibular bone within our model is modeled as homogeneous and isotropic. Cortical and cancellous differentiation incorporation can improve predictions of stress localization. Muscle contribution: No muscle forces were included in simulations that can provide stabilizing preload in vivo. Fracture propagation: The model does not simulate real crack initiation and failure limits but forecasts stress, strain, and displacement. Experimental verification: Clinical or cadaveric data in microgravity conditions is lacking; prospective physical models or in vitro research may provide substance to these findings. The condyles were fully fixed, which standardized loading but does not replicate the physiological compliance of the temporomandibular joint, likely underestimating differences between normal and osteoporotic mandibles. Microgravity was simulated by removing gravitational acceleration, without accounting for systemic physiological changes (e.g., altered remodelling, fluid shifts) that occur during spaceflight. Conclusion This study explored biomechanical response of mandibular angle fracture under traumatic loading in Earth gravity and microgravity through finite element analysis. Applying a 2000 N force in the 45° posterosuperior direction to simulate moderate-to-severe trauma impact, we compared the biomechanical response of healthy and osteoporotic bone models. Findings indicate that stress distribution was largely gravity-insensitive, but strain and total deformation nearly doubled in microgravity. This reduced stress in osteoporotic bone was associated with concordant deformation patterns, suggesting compounded risk during spaceflight. These results underscore the importance of considering gravitational loading in maxillofacial biomechanics and justify promotion of protection for astronauts on long-duration spaceflight. Declarations Acknowledgements The authors sincerely thanks friends and peers for their encouragement and moral support throughout the course of this project. No external funding or institutional support was involved in the completion of this study. Author Information Authors and Affiliations Department of Oral and maxillofacial surgery, KMCT Dental College, Calicut, Kerala, India, 673602 Sidharth Manoj (Final year Post graduate student) Manoj Kumar K P (Principal & Head of the department) Vipin Das A P (Associate Professor) Contributions S.M wrote the main manuscript text and analysed the collected data. V.D helped in collecting the data. M.K helped oversee the project and edited the manuscript. All authors reviewed the manuscript. Corresponding Author Correspondance to Sidharth Manoj Ethics Declarations Competing interests The authors declare no financial or non-financial competing interests. Ethics and Informed Consent Statements This study did not involve human participants, animal experiments, or clinical data. Therefore, ethical approval was not required. Data Availability All data generated or analysed during this study are included in this published article. References Srinivasan B, Balakrishna R, Sudarshan H, Veena G, Prabhakar S. Retrospective analysis of 162 mandibular fractures: An institutional experience. Annals of Maxillofacial Surgery. 2019;9(1):124. Rashid A, Eyeson J, Haider D, van Gijn D, Fan K. Incidence and patterns of mandibular fractures during a 5-year period in a London teaching hospital. British Journal of Oral and Maxillofacial Surgery. 2013;51(8):794–8. Choi AH, Conway RC, Taraschi V, Besim Ben-Nissan. Biomechanics and functional distortion of the human mandible. Journal of Investigative and Clinical Dentistry. 2015;6(4):241–51. Vijayaraghavan Nv, Ramesh G, Thareja A, Patil S. Masticatory efficiency after rehabilitation of acquired maxillary and mandibular defects. Indian Journal of Dentistry. 2015;6(3):139. Man J, Graham T, Squires-Donelly G, Laslett AL. The effects of microgravity on bone structure and function. npj Microgravity [Internet]. 2022;8(1):1–15. Gabel L, Liphardt AM, Hulme PA, Heer M, Zwart SR, Sibonga JD, et al. Incomplete recovery of bone strength and trabecular microarchitecture at the distal tibia 1 year after return from long duration spaceflight. Scientific Reports [Internet]. 2022;12(1):9446. Stavnichuk M, Mikolajewicz N, Corlett T, Morris M, Komarova SV. A systematic review and meta-analysis of bone loss in space travelers. npj Microgravity [Internet]. 2020;6(1). Baran R, Wehland M, Schulz H, Heer M, Infanger M, Grimm D. Microgravity-Related Changes in Bone Density and Treatment Options: A Systematic Review. International Journal of Molecular Sciences. 2022;23(15):8650. Moussa MS, Goldsmith M, Komarova SV. Craniofacial Bones and Teeth in Spacefarers: Systematic Review and Meta-analysis. JDR Clinical & Translational Research. 2022;238008442210849. Ghosh P, Stabley JN, Behnke BJ, Allen MR, Delp MD. Effects of spaceflight on the murine mandible: Possible factors mediating skeletal changes in non-weight bearing bones of the head. Bone. 2016;83:156–61. Rai B, Kaur J, Catalina M. Bone mineral density, bone mineral content, gingival crevicular fluid (matrix metalloproteinases, cathepsin K, osteocalcin), and salivary and serum osteocalcin levels in human mandible and alveolar bone under conditions of simulated microgravity. Journal of Oral Science. 2010;52(3):385–90. Review of NASA’s Evidence Reports on Human Health Risks. National Academies Press eBooks. 2018. Kirchen ME, O’connor KM, Gruber HE, Sweeney JR, Fras IA, Stover SJ, et al. Effects of microgravity on bone healing in a rat fibular osteotomy model. PubMed. 1995;(318):231–42. Lisiak-Myszke M, Marciniak D, Bieliński M, Sobczak H, Garbacewicz Ł, Drogoszewska B. Application of Finite Element Analysis in Oral and Maxillofacial Surgery—A Literature Review. Materials. 2020;13(14):3063. Hedeșiu M, Pavel DG, Almășan O, Pavel SG, Hedeșiu H, Rafiroiu D. Three-Dimensional Finite Element Analysis on Mandibular Biomechanics Simulation under Normal and Traumatic Conditions. Oral [Internet]. 2022 Sep 1 [cited 2023 Jan 24];2(3):221–37. Wang H, Ji B, Jiang W, Liu L, Zhang P, Tang W, et al. Three-Dimensional Finite Element Analysis of Mechanical Stress in Symphyseal Fractured Human Mandible Reduced With Miniplates During Mastication. Journal of Oral and Maxillofacial Surgery. 2010;68(7):1585–92. Arbag H, Korkmaz HH, Ozturk K, Uyar Y. Comparative Evaluation of Different Miniplates for Internal Fixation of Mandible Fractures Using Finite Element Analysis. Journal of Oral and Maxillofacial Surgery. 2008;66(6):1225–32. Turner CH, Rho J, Takano Y, Tsui TY, Pharr GM. The elastic properties of trabecular and cortical bone tissues are similar: results from two microscopic measurement techniques. Journal of Biomechanics. 1999;32(4):437–41. Subit D, Eduardo, Valazquez-Ameijide J, Arregui-Dalmases C, Crandall J. Tensile material properties of human rib cortical bone under quasi-static and dynamic failure loading and influence of the bone microstucture on failure characteristics. arXiv (Cornell University). 2011; Nail Beisekenov, Marzhan Sadenova, Bagdat Azamatov, Syrnev B. Analysis of Biomechanical Characteristics of Bone Tissues Using a Bayesian Neural Network: A Narrative Review. Journal of Functional Biomaterials [Internet]. 2025 May 8 [cited 2025 Jul 18];16(5):168–8. Jimenez-Palomar I, Shipov A, Shahar R, Barber AH. Mechanical Behavior of Osteoporotic Bone at Sub-Lamellar Length Scales. Frontiers in Materials. 2015;2. Bahadır Sancar, Yunus Çetiner, Ertunç Dayı. Evaluation of the pattern of fracture formation from trauma to the human mandible with finite element analysis. Part 2: The corpus and the angle regions. Dental Traumatology. 2023;39(5):437–47. Liu Y, Wang R, Baur DA, Jiang Xianfeng. A finite element analysis of the stress distribution to the mandible from impact forces with various orientations of third molars. Journal of Zhejiang University-science B. 2018;19(1):38–48. M. Unnewehr, Homann C, Schmidt PF, P. Sotony, Fischer G, Brinkmann B, et al. Fracture properties of the human mandible. International Journal of Legal Medicine. 2003;117(6):326–30. Daniel RW, Weisenbach CA, McGovern SM, Rooks TF, Chancey VC, Brozoski FT. Fracture Injury Risk of the Restrained Mandible to Anterior–Posterior Blunt Impacts. Journal of Biomechanical Engineering. 2021;143(4). Zimmermann EA, Schaible E, Gludovatz B, Schmidt FN, Riedel C, Krause M, et al. Intrinsic mechanical behavior of femoral cortical bone in young, osteoporotic and bisphosphonate-treated individuals in low- and high energy fracture conditions. Scientific Reports. 2016;6(1). Ioana Duncea, Bacali C, Smaranda Buduru, Ioana Scrobota, Oana Almășan. The Association of Systemic and Mandibular Bone Mineral Density in Postmenopausal Females with Osteoporosis. Medicina. 2024;60(8):1313–3. Gulsahi A. Osteoporosis and jawbones in women. Journal of International Society of Preventive and Community Dentistry. 2015;5(4):263. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 02 Mar, 2026 Read the published version in npj Microgravity → Version 1 posted Editorial decision: Revision requested 28 Oct, 2025 Reviews received at journal 09 Oct, 2025 Reviews received at journal 06 Oct, 2025 Reviewers agreed at journal 01 Oct, 2025 Reviewers agreed at journal 29 Sep, 2025 Reviewers invited by journal 29 Sep, 2025 Editor assigned by journal 27 Sep, 2025 Submission checks completed at journal 15 Sep, 2025 First submitted to journal 03 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7531616","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":509979888,"identity":"031bf4d5-e4cc-4e30-96a5-b7168f5a1591","order_by":0,"name":"Sidharth 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08:48:25","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":244402,"visible":true,"origin":"","legend":"\u003cp\u003eTotal deformation of healthy bone under gravity.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/ab86d21690f8a339533f12d6.png"},{"id":90975022,"identity":"04eb564f-d49f-4fa7-8ea4-962e8f3ad0f5","added_by":"auto","created_at":"2025-09-10 08:24:27","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":222342,"visible":true,"origin":"","legend":"\u003cp\u003eEquivalent stress of osteoporotic bone under gravity.\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/66b2b14ade65ef47f90e73bf.png"},{"id":90975353,"identity":"5dd60645-cd5e-4123-8d8b-6c5d3d15e07a","added_by":"auto","created_at":"2025-09-10 08:32:25","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":224037,"visible":true,"origin":"","legend":"\u003cp\u003eElastic strain of osteoporotic bone under gravity.\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/93010e6d9ca673e4ea49bb13.png"},{"id":90974979,"identity":"5fbad91f-c874-400b-8328-ee1adb79ce8f","added_by":"auto","created_at":"2025-09-10 08:24:25","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":245716,"visible":true,"origin":"","legend":"\u003cp\u003eTotal deformation of osteoporotic bone under gravity.\u003c/p\u003e","description":"","filename":"image10.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/28ee43817eaf431656d129e0.png"},{"id":90976530,"identity":"45dd335b-f527-4b47-b339-1de567d1cb1a","added_by":"auto","created_at":"2025-09-10 08:40:25","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":234256,"visible":true,"origin":"","legend":"\u003cp\u003eEquivalent stress of healthy bone under micro gravity.\u003c/p\u003e","description":"","filename":"image11.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/b5e26db3c8515a38a0d6dc51.png"},{"id":90975377,"identity":"88dea82b-4355-46da-b7cf-8dd6c254bce5","added_by":"auto","created_at":"2025-09-10 08:32:27","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":236415,"visible":true,"origin":"","legend":"\u003cp\u003eElastic strain of healthy bone under micro gravity.\u003c/p\u003e","description":"","filename":"image12.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/ef89f12a390296dc061b1766.png"},{"id":90974999,"identity":"a0a26134-02d4-4530-b194-332f7883168d","added_by":"auto","created_at":"2025-09-10 08:24:26","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":246643,"visible":true,"origin":"","legend":"\u003cp\u003eTotal deformation of healthy bone under micro gravity.\u003c/p\u003e","description":"","filename":"image13.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/851336d83943d297a1856cf2.png"},{"id":90974997,"identity":"409ba7f9-d4f3-42a8-bf15-e967b497ab6c","added_by":"auto","created_at":"2025-09-10 08:24:26","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":224653,"visible":true,"origin":"","legend":"\u003cp\u003eEquivalent stress of osteoporotic bone under micro gravity.\u003c/p\u003e","description":"","filename":"image14.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/176f383197a79e41c42741f9.png"},{"id":90975357,"identity":"3e1f06ab-f2dc-4790-9498-ce7fe938850d","added_by":"auto","created_at":"2025-09-10 08:32:25","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":224421,"visible":true,"origin":"","legend":"\u003cp\u003eElastic strain of osteoporotic bone under micro gravity.\u003c/p\u003e","description":"","filename":"image15.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/09e82824542b5009cf5f09fe.png"},{"id":90975364,"identity":"303e1944-a574-4824-9bc9-6885103ff11e","added_by":"auto","created_at":"2025-09-10 08:32:26","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":237265,"visible":true,"origin":"","legend":"\u003cp\u003eTotal deformation of osteoporotic bone under micro gravity.\u003c/p\u003e","description":"","filename":"image16.png","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/2a723badab3c32a8abd31d6f.png"},{"id":104250633,"identity":"19d2b79a-9d6e-4472-9372-fb63733f3fa3","added_by":"auto","created_at":"2026-03-09 16:02:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4098491,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7531616/v1/f08c15d5-ea98-4989-801f-f07614c1a350.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Behaviour of Mandibular Fractures under Earth and Microgravity conditions: A Finite Element Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe maxillofacial region being one of the most exposed parts of the body is highly susceptible to trauma. Common causes of maxillofacial trauma include fall, traffic accidents, interpersonal violence and sports injuries \u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. Of all maxillofacial trauma 42% attribute to mandibular fractures which includes angle fractures (30%), parasymphysis fractures (27%), condylar fractures (27%), body fractures (9%), symphyseal fractures (4%), ramus fractures (3%) and then the coronoid (\u0026le;\u0026thinsp;1%) \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. Biomechanical integrity of the mandible is a necessity for proper speech, mastication and protection of the lower airway and a fracture disrupts this integrity making them clinically significant \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn the context of long duration spaceflights, the fracture biomechanics is more complex. Long exposures to zero gravity/ microgravity causes marked decrease in bone mineral density and disruption of its trabecular pattern due to a condition called as spaceflight osteopenia \u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. Studies shows that astronauts loose about 1-1.5% of their bone mass every month under microgravity because of the absence of mechanical loading which normally induces bone remodelling \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. Maxillofacial region though not studied extensively are not exempted from these degenerative changes \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eAdding to this is the risk of traumatic injuries in space including unintentional collision with spacecraft equipment, free floating impact or emergency events. Even minor trauma could have more severe repercussions in space where bone weakness is increased and healing is not properly understood \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. As many space missions extend beyond low earth orbit it is necessary to understand the biomechanics of maxillofacial trauma in microgravity.\u003c/p\u003e\u003cp\u003eAs technology advances newer methods have risen to better understand biomechanics of orthopaedic and maxillofacial bones, one of them being the Finite Element Analysis (FEA) which is being widely used as a predictive tool to evaluate stress-strain response of bones under various loading conditions \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. FEA of the mandible has been used to understand fracture risk; fracture fixation stability and study how occlusal loads are transferred \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. FEA studies though highly versatile and efficient no studies have emphasized the biomechanical behaviour of mandible under altered gravitational environments.\u003c/p\u003e\u003cp\u003eTo address this gap this study focuses on the use of FEA to compare mandible specifically the angle subjected to trauma under Earth\u0026rsquo;s gravity and microgravity. Also, two different bone qualities of mandible are used in the study that is healthy mandible and an osteoporotic mandible. The aim of this study is to evaluate the biomechanical behaviour of mandibular angle under a moderate to high impact trauma under gravity and microgravity. From the simulation of trauma to osteoporotic and normal bone we aim to quantify the effects of gravitational unloading on fracture risk and deformation patterns.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eA CT scan of a human mandible was obtained as a DICOM file which was imported to a CAD software called Fusion 360 (Autodesk, USA). The 3D volume was converted to a surface mesh so that the entire mandible would be recognized as a solid by the FEA software (Ansys) which was then exported as a STEP file.\u003c/p\u003e\u003cp\u003eThe STEP file was imported into Ansys Workbench 2025 R1 (Ansys Inc., USA) using SpaceClaim (a CAD tool integrated within Ansys) where some geometric refinements and mesh optimizations were performed (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). For the model meshing was done using a tetrahedral patch independent mesh with an elemental size of 0.3mm to ensure adequate resolution at structurally significant areas like the angle and condyles.\u003c/p\u003e\u003cp\u003eWithin the engineering data module of Ansys two custom material profiles were created to represent healthy and osteoporotic bones. They were given the following properties \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eProperties of healthy and osteoporotic bones.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBone type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDensity\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYoungs modulus\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePoisson\u0026rsquo;s Ratio\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHealthy bone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1900 Kg/ m\u0026sup3;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 GPa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOsteoporotic bone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1500 Kg/ m\u0026sup3;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 GPa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe prepared model was then imported to static structural environment within Ansys and four of the following simulations were tested\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eHealthy bone under Earth gravity (1g)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eOsteoporotic bone under Earth gravity\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eHealthy bone under microgravity (0g)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eOsteoporotic bone under microgravity\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eIn all cases fixed supports were applied at the condyles (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) to simulate the temporomandibular joint. For models involving gravity, the standard earth gravity (9.81m/s\u0026sup2;) setting was applied which resulted in a gravitational force in the negative Z direction (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTo simulate trauma a force of 2000N at angle of 45\u0026deg; posterosuperiorly was given at the right mandibular angle, corresponding to the vector of a moderate to a high impact blow that may occur during interpersonal violence or accidental impact \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eAfter the boundary conditions were set the models were solved under linear elastic assumptions and outcomes of each simulation were described in terms of\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eEquivalent (von Mises) stress\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eElastic strain\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eTotal deformation\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThese results were compared to understand the role of bone quality and gravitational forces on mandibular biomechanics under trauma\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eFEA was performed on the mandibular models under four distinct conditions. Healthy and Osteoporotic bones were tested under Earth\u0026rsquo;s gravity and microgravity. The results were expressed as equivalent (von Mises) stress, elastic strain, and total deformation. The summarized results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of results obtained under different bone types and gravity.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCondition\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEquivalent stress\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eElastic strain\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTotal deformation\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHealthy bone under gravity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.1021e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.098353\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.00127\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOsteoporotic bone under gravity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.1017e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.098317\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.0012683\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHealthy bone under micro gravity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.1021e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.19669\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.0025393\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOsteoporotic bone under micro gravity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.017e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.19663\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.0025365\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eUnder Earth gravity, both normal and osteoporotic bone possessed nearly similar stress values (~\u0026thinsp;1.1 GPa) with less than 1% difference in deformation and strain. Under microgravity, both conditions elastic strain and overall deformation nearly doubled as compared to their Earth counterparts. Despite the increased deformation and strain, stress values were nearly the same, suggesting that gravity played no role in the internal force distribution but in displacement and material extension.\u003c/p\u003e\u003cp\u003eCuriously, the osteoporotic bone in microgravity was under lower stress (1.017 \u0026times; 10⁹ Pa) than healthy bone but with practically the same strain and deformation. This could be indicative of an impaired load-carrying capability due to impaired stiffness and density, demonstrating the vulnerability of impaired bone tissue in low-gravity conditions.\u003c/p\u003e\u003cp\u003eBelow are the results of the FEA:\u003c/p\u003e\n\u003ch3\u003eHealthy bone under gravity\u003c/h3\u003e\n\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eOsteoporotic bone under gravity\u003c/h3\u003e\n\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eHealthy bone under micro gravity\u003c/h3\u003e\n\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eOsteoporotic bone under micro gravity\u003c/h3\u003e\n\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis finite element analysis demonstrated that microgravity significantly alters mandibular biomechanical response to trauma and that the effect is enhanced in osteoporotic bone. We present our findings below in the context of the literature.\u003c/p\u003e\u003cp\u003eExperimental data from postmortem human mandibles indicate that fracture thresholds at the condyle and mandibular angle are approximately 2,800 N in the condition of restrained impact loading \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e. Finite element and experimental studies with controlled direction and magnitude of loading always apply forces of approximately 2,000 N at 45\u0026deg; angulation and induce clinically relevant fracture patterns at the mandible angle \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. These findings justify our choosing a 2,000 N, posterosuperiorly directed, 45\u0026deg; trauma vector to model moderate-to-severe impacts.\u003c/p\u003e\u003cp\u003eOur finding that elastic strain and deformation nearly doubled under microgravity is consistent with known alterations in bone response in space. While long bones are well described for microgravity-induced bone loss, craniofacial bones like the mandible are not immune to loss. Simulated microgravity models have shown substantial reductions in mandibular and alveolar bone density and increased resorption markers in males and females \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. Similarly, micro-CT analysis in rodents has described substantial mandibular microstructure alterations under spaceflight conditions \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. In gravity osteoporotic bone shows only a minimal increase in deformation compared to healthy bone, because the fixed condyle boundary condition dominates structural response, the same reason implies to normal and osteoporotic bone in microgravity as they do not allow any kind of movements.\u003c/p\u003e\u003cp\u003eAlso, evidence shows osteoporosis lowers bone stiffness and density, which renders it more susceptible to deformation during loading. Experimental testing reveals cortical bone densities in osteoporotic human mandibles to be much lower than that of control healthy subjects, corresponding to reduced elastic modulus (\u0026lt;\u0026thinsp;10 GPa) and bone mineral density. These results favour both the modulus and density differences used by our model \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eBiomechanical implications of gravity removal\u003c/h3\u003e\n\u003cp\u003eMost FEA trauma analysis ignore gravity on the grounds that high-magnitude forces dominate gravity's effects in brief simulations. However, comparison suggests exclusion of preload under gravity causes greater displacement and strain under identical external loads. Facial bones do not support weight in the conventional sense, so facial structures react differently when gravity is ignored: the mandible is more freely mobile, with no counterforce to dissipate impact energy \u0026mdash; this removes baseline tissue resistance and allows more deformation.\u003c/p\u003e\n\u003ch3\u003eClinical and spaceflight relevance\u003c/h3\u003e\n\u003cp\u003eThe microgravity-induced doubling of strain and deformation poses important concerns over fracture tolerance thresholds in astronauts, particularly those with osteopenia due to spaceflight. Even small impact events such as equipment strikes, floating strikes, or inadvertent drops could be beyond the tolerance of weakened craniofacial bones. This is compelling evidence supporting protective craniofacial equipment, trauma prevention protocols, and pre-launch screening for astronaut applicants for bone mineral density.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eLimitation and future directions\u003c/h2\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eBone heterogeneity: Mandibular bone within our model is modeled as homogeneous and isotropic. Cortical and cancellous differentiation incorporation can improve predictions of stress localization.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMuscle contribution: No muscle forces were included in simulations that can provide stabilizing preload in vivo.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eFracture propagation: The model does not simulate real crack initiation and failure limits but forecasts stress, strain, and displacement.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eExperimental verification: Clinical or cadaveric data in microgravity conditions is lacking; prospective physical models or in vitro research may provide substance to these findings.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe condyles were fully fixed, which standardized loading but does not replicate the physiological compliance of the temporomandibular joint, likely underestimating differences between normal and osteoporotic mandibles.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMicrogravity was simulated by removing gravitational acceleration, without accounting for systemic physiological changes (e.g., altered remodelling, fluid shifts) that occur during spaceflight.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study explored biomechanical response of mandibular angle fracture under traumatic loading in Earth gravity and microgravity through finite element analysis. Applying a 2000 N force in the 45\u0026deg; posterosuperior direction to simulate moderate-to-severe trauma impact, we compared the biomechanical response of healthy and osteoporotic bone models. Findings indicate that stress distribution was largely gravity-insensitive, but strain and total deformation nearly doubled in microgravity. This reduced stress in osteoporotic bone was associated with concordant deformation patterns, suggesting compounded risk during spaceflight. These results underscore the importance of considering gravitational loading in maxillofacial biomechanics and justify promotion of protection for astronauts on long-duration spaceflight.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cu\u003eAcknowledgements\u0026nbsp;\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors sincerely thanks friends and peers for their encouragement and moral support throughout the course of this project. No external funding or institutional support was involved in the completion of this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eAuthor Information\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAuthors and Affiliations\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDepartment of Oral and maxillofacial surgery, KMCT Dental College, Calicut, Kerala, India, 673602\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSidharth Manoj (Final year Post graduate student)\u003c/p\u003e\n\u003cp\u003eManoj Kumar K P (Principal \u0026amp; Head of the department)\u003c/p\u003e\n\u003cp\u003eVipin Das A P (Associate Professor)\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eContributions\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eS.M wrote the main manuscript text and analysed the collected data. V.D helped in collecting the data. M.K helped oversee the project and edited the manuscript. All authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eCorresponding Author\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondance to Sidharth Manoj\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eEthics Declarations\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eCompeting interests\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no financial or non-financial competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eEthics and Informed Consent Statements\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThis study did not involve human participants, animal experiments, or clinical data. Therefore, ethical approval was not required.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eData Availability\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during this study are included in this published article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSrinivasan B, Balakrishna R, Sudarshan H, Veena G, Prabhakar S. Retrospective analysis of 162 mandibular fractures: An institutional experience. Annals of Maxillofacial Surgery. 2019;9(1):124.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRashid A, Eyeson J, Haider D, van Gijn D, Fan K. Incidence and patterns of mandibular fractures during a 5-year period in a London teaching hospital. British Journal of Oral and Maxillofacial Surgery. 2013;51(8):794\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChoi AH, Conway RC, Taraschi V, Besim Ben-Nissan. Biomechanics and functional distortion of the human mandible. Journal of Investigative and Clinical Dentistry. 2015;6(4):241\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVijayaraghavan Nv, Ramesh G, Thareja A, Patil S. Masticatory efficiency after rehabilitation of acquired maxillary and mandibular defects. Indian Journal of Dentistry. 2015;6(3):139.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMan J, Graham T, Squires-Donelly G, Laslett AL. The effects of microgravity on bone structure and function. npj Microgravity [Internet]. 2022;8(1):1\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGabel L, Liphardt AM, Hulme PA, Heer M, Zwart SR, Sibonga JD, et al. Incomplete recovery of bone strength and trabecular microarchitecture at the distal tibia 1 year after return from long duration spaceflight. Scientific Reports [Internet]. 2022;12(1):9446.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStavnichuk M, Mikolajewicz N, Corlett T, Morris M, Komarova SV. A systematic review and meta-analysis of bone loss in space travelers. npj Microgravity [Internet]. 2020;6(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaran R, Wehland M, Schulz H, Heer M, Infanger M, Grimm D. Microgravity-Related Changes in Bone Density and Treatment Options: A Systematic Review. International Journal of Molecular Sciences. 2022;23(15):8650.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoussa MS, Goldsmith M, Komarova SV. Craniofacial Bones and Teeth in Spacefarers: Systematic Review and Meta-analysis. JDR Clinical \u0026amp; Translational Research. 2022;238008442210849.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGhosh P, Stabley JN, Behnke BJ, Allen MR, Delp MD. Effects of spaceflight on the murine mandible: Possible factors mediating skeletal changes in non-weight bearing bones of the head. Bone. 2016;83:156\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRai B, Kaur J, Catalina M. Bone mineral density, bone mineral content, gingival crevicular fluid (matrix metalloproteinases, cathepsin K, osteocalcin), and salivary and serum osteocalcin levels in human mandible and alveolar bone under conditions of simulated microgravity. Journal of Oral Science. 2010;52(3):385\u0026ndash;90.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eReview of NASA\u0026rsquo;s Evidence Reports on Human Health Risks. National Academies Press eBooks. 2018.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKirchen ME, O\u0026rsquo;connor KM, Gruber HE, Sweeney JR, Fras IA, Stover SJ, et al. Effects of microgravity on bone healing in a rat fibular osteotomy model. PubMed. 1995;(318):231\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLisiak-Myszke M, Marciniak D, Bieliński M, Sobczak H, Garbacewicz Ł, Drogoszewska B. Application of Finite Element Analysis in Oral and Maxillofacial Surgery\u0026mdash;A Literature Review. Materials. 2020;13(14):3063.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHedeșiu M, Pavel DG, Almășan O, Pavel SG, Hedeșiu H, Rafiroiu D. Three-Dimensional Finite Element Analysis on Mandibular Biomechanics Simulation under Normal and Traumatic Conditions. Oral [Internet]. 2022 Sep 1 [cited 2023 Jan 24];2(3):221\u0026ndash;37.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang H, Ji B, Jiang W, Liu L, Zhang P, Tang W, et al. Three-Dimensional Finite Element Analysis of Mechanical Stress in Symphyseal Fractured Human Mandible Reduced With Miniplates During Mastication. Journal of Oral and Maxillofacial Surgery. 2010;68(7):1585\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArbag H, Korkmaz HH, Ozturk K, Uyar Y. Comparative Evaluation of Different Miniplates for Internal Fixation of Mandible Fractures Using Finite Element Analysis. Journal of Oral and Maxillofacial Surgery. 2008;66(6):1225\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTurner CH, Rho J, Takano Y, Tsui TY, Pharr GM. The elastic properties of trabecular and cortical bone tissues are similar: results from two microscopic measurement techniques. Journal of Biomechanics. 1999;32(4):437\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSubit D, Eduardo, Valazquez-Ameijide J, Arregui-Dalmases C, Crandall J. Tensile material properties of human rib cortical bone under quasi-static and dynamic failure loading and influence of the bone microstucture on failure characteristics. arXiv (Cornell University). 2011;\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNail Beisekenov, Marzhan Sadenova, Bagdat Azamatov, Syrnev B. Analysis of Biomechanical Characteristics of Bone Tissues Using a Bayesian Neural Network: A Narrative Review. Journal of Functional Biomaterials [Internet]. 2025 May 8 [cited 2025 Jul 18];16(5):168\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJimenez-Palomar I, Shipov A, Shahar R, Barber AH. Mechanical Behavior of Osteoporotic Bone at Sub-Lamellar Length Scales. Frontiers in Materials. 2015;2.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBahadır Sancar, Yunus \u0026Ccedil;etiner, Ertun\u0026ccedil; Dayı. Evaluation of the pattern of fracture formation from trauma to the human mandible with finite element analysis. Part 2: The corpus and the angle regions. Dental Traumatology. 2023;39(5):437\u0026ndash;47.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu Y, Wang R, Baur DA, Jiang Xianfeng. A finite element analysis of the stress distribution to the mandible from impact forces with various orientations of third molars. Journal of Zhejiang University-science B. 2018;19(1):38\u0026ndash;48.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. Unnewehr, Homann C, Schmidt PF, P. Sotony, Fischer G, Brinkmann B, et al. Fracture properties of the human mandible. International Journal of Legal Medicine. 2003;117(6):326\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDaniel RW, Weisenbach CA, McGovern SM, Rooks TF, Chancey VC, Brozoski FT. Fracture Injury Risk of the Restrained Mandible to Anterior\u0026ndash;Posterior Blunt Impacts. Journal of Biomechanical Engineering. 2021;143(4).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZimmermann EA, Schaible E, Gludovatz B, Schmidt FN, Riedel C, Krause M, et al. Intrinsic mechanical behavior of femoral cortical bone in young, osteoporotic and bisphosphonate-treated individuals in low- and high energy fracture conditions. Scientific Reports. 2016;6(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIoana Duncea, Bacali C, Smaranda Buduru, Ioana Scrobota, Oana Almășan. The Association of Systemic and Mandibular Bone Mineral Density in Postmenopausal Females with Osteoporosis. Medicina. 2024;60(8):1313\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGulsahi A. Osteoporosis and jawbones in women. Journal of International Society of Preventive and Community Dentistry. 2015;5(4):263.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-microgravity","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjmgrav","sideBox":"Learn more about [npj Microgravity](http://www.nature.com/npjmgrav/)","snPcode":"41526","submissionUrl":"https://submission.springernature.com/new-submission/41526/3","title":"npj Microgravity","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Mandible, Angle fracture, Finite element analysis, Microgravity, Osteoporosis, Spaceflight medicine, Maxillofacial trauma, Gravity","lastPublishedDoi":"10.21203/rs.3.rs-7531616/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7531616/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMaxillofacial fractures especially that of the mandible pose a significant risk under microgravity environments because astronauts experience progressive bone loss during long duration flights because of skeletal unloading. In this study we explore the biomechanical response of mandibular angle under high impact trauma under Earth\u0026rsquo;s gravity and microgravity. A human mandibular model was subjected to a force of 2000N force at angle of 45\u0026deg; which was directed posterosuperiorly at the right angle region with simulations comparing healthy and osteoporotic bone (bone loses its density in long flights due to skeletal unloading). The results revealed that although stresses remained the same across all conditions microgravity caused nearly double the strain and deformation indicating high risk of fracture. These findings emphasise the need for biomechanical evaluation and protective strategies in space medicine.\u003c/p\u003e","manuscriptTitle":"Behaviour of Mandibular Fractures under Earth and Microgravity conditions: A Finite Element Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-10 08:24:20","doi":"10.21203/rs.3.rs-7531616/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-28T07:49:19+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-09T17:02:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-06T21:45:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"118693029394371361706689110166378523317","date":"2025-10-01T10:19:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"293730716652937992241225238026932947554","date":"2025-09-30T01:30:04+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-29T05:17:26+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-27T16:59:51+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-15T13:56:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"npj Microgravity","date":"2025-09-04T03:22:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-microgravity","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjmgrav","sideBox":"Learn more about [npj Microgravity](http://www.nature.com/npjmgrav/)","snPcode":"41526","submissionUrl":"https://submission.springernature.com/new-submission/41526/3","title":"npj Microgravity","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5ab8995d-d2aa-48a4-a657-76a557582750","owner":[],"postedDate":"September 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":54165959,"name":"Health sciences/Diseases"},{"id":54165960,"name":"Health sciences/Health care"},{"id":54165961,"name":"Health sciences/Medical research"},{"id":54165962,"name":"Biological sciences/Physiology"}],"tags":[],"updatedAt":"2026-03-09T16:00:57+00:00","versionOfRecord":{"articleIdentity":"rs-7531616","link":"https://doi.org/10.1038/s41526-025-00558-w","journal":{"identity":"npj-microgravity","isVorOnly":false,"title":"npj Microgravity"},"publishedOn":"2026-03-02 15:57:10","publishedOnDateReadable":"March 2nd, 2026"},"versionCreatedAt":"2025-09-10 08:24:20","video":"","vorDoi":"10.1038/s41526-025-00558-w","vorDoiUrl":"https://doi.org/10.1038/s41526-025-00558-w","workflowStages":[]},"version":"v1","identity":"rs-7531616","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7531616","identity":"rs-7531616","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}